The proliferation of sensor technology, along with advances in wireless communication and mobile devices, allow context-aware applications. These applications need context information, which should be shared between different applications to reduce the effort of modeling, obtaining, and managing. In the Nexus project, a context sharing platform was developed that allows for global, open context access of different applications. In this paper, different aspects of this work are illustrated: how a global access can be achieved by a federation approach, how these models can be active to support event observation and notification, how the third dimension can be introduced in the modeling and finally, how this leads to advanced applications that augment our reality with virtual information. Finally, an outlook into the vision of the World Wide Space is given.